Spark-plug.



E. BLATTMANN.

.'SPARK PLUG. APPLICATION FILED SEPT. s. 1913.

Patented May 2, 1916.

ERNST iinirsn sass rand BLATTMANN, 0F BERLIN-NONNENDAMM, GERMANY, ASSIGNOR TD SIEMENS 8E HALSKE A.-G., 0F BERLIN, GERMANY, A CORPORATION OF GERMANY.

SPARK-PLUG.

Specification of Letters Patent.

Patented May 2, 1918.

Application filed September 3, 1913. Serial No. 787,989.

11') all whom it may concern Be it known that I. Enxsr BLAT'IBIANN,

a German citizen. and. resident of Berlin- Nonnendannn, (irermany, have invented certain new and useful Improvements in Spark-Plugs, of which the following is a specification.

This invention relates to a spark plug for combustion engines, in which the middle electrode is provided with a bore-hole separated from the exterior air, the discharge opening of said bore-hole being opposite to an electrode for choking oil the discharge gas. I

The drawing shows in a cross-section one form of a spark plug according to my invention.

1 is the middle electrode having a borehole 2 which is shown dotted 3 is the electrode which is mounted in the c dug 5, and 4 and (3 are insulating bodies. During the operation of the present spark plug at each compression stroke a combustible mixture is pressed into the bore-hole 2 which mixture, when discharging through the bore-hole, will be ignited and throttled at the spark gap by the c u:liter-electrode 3. The blast ingr effect due to the discharge of the gas I will thus keep the points of the spark gap always in a clean condition. In order that the hollow electrode may not become too hot during operation. it is zulvantagrcmlsly' surrounded by an insulating body 4: which is of.

such form and dimensions that between electrode and insulating body a small space will be left free. 'lhisnnddle electrode is made conical at its lower end, in order to obtain a broad spark and in order to prevent the formation of scrap at the spark points. The

deposit of scrap, otherwise, mar erentualb become so large that it will (1: e a SllCltcircuit with the counter-electrcdc.

The contiter-electrode 3 which is mount ed in the interior of the casing 5 shali remain entirely within this casing and be protected against injury. For this purpose the counter-clectrode is mounted in a cut-out oi the casing Since in this case the-spark points are positioned in the interior o the casing and cove-red up from underlie-am by the electrode which is inserted into the 021s ing, one. or more openings '7 are provided through which the distance of the electrodes may be observed and adjusted from the side if desired.

. Having thus described my invention I herewith claim as new and desire to secure by Letters Patent ot' the Unite-- U ing therefrom during expansion and one or *more openings in the wall of said casmg for istance beadjusting and observing the tween said electrodes.

In witness whereot I have hereunto set my. signature in the presence of two sub- 

